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92 series Electronic Weighing Feeder

key word:Heat exchange element

Category:


Product description

92 Series Electronic weighing coal feeder

 

1. Introduction

1.1. Purpose

It is mainly used in coal pulverizing system of boiler in thermal power plant. According to the requirements of combustion system, it can accurately and quantitatively transport raw coal, and has the function of automatic regulation and control.

1.2. Model meaning

92 - **

92 -- Code of electronic weighing coal feeder

**---Nominal diameter of feed inlet, in inch

1.3. Technical features

1.3.1. Technical performance characteristics:

1.3.1.1. Coal feeding rate accuracy of coal feeder: ±0.5% metering accuracy.

1.3.1.2. The coal feeder can feed coal continuously and evenly with accurate weighing. It can automatically adjust the coal feeding amount according to the boiler combustion system, so as to match the actual coal feeding amount with the boiler load.

1.3.1.3. The coal feeder is provided with pressure resistant shell, and the shell is equipped with lighting lamp, and the end of shell is provided with access door.

1.3.1.4. The metering and conveying part of the coal feeder can be pulled out from the shell for easy adjustment and maintenance.

1.3.1.5. The main driving drum of coal feeder has anti-skid function.

1.3.1.6. The belt of coal feeder is equipped with skirt on two sides to prevent coal particles from scattering; flange is provided in the middle to prevent belt deviation.

1.3.1.7. The coal feeder is equipped with scraper cleaning chain device.

1.3.1.8. Reliable adjustment device shall be adopted for coal feeder.

1.3.1.9. The electronic control system can calculate and display instantaneous coal feeding rate and cumulative coal feeding quantity.

1.3.1.10. The electronic control system can automatically set the coal feeding amount to meet the requirements of combustion system.

1.3.1.11. It has alarm and protection functions for abnormal conditions such as coal cut-off, coal blockage and insufficient coal loading.

1.3.1.12. The coal gate can be opened and closed manually and electrically with high corrosion resistance and sealing performance.

1.3.1.13. All parts in direct contact with coal flow shall be made of stainless steel.

1.3.1.14. The noise at 1m away from the equipment shell shall not exceed 85dB (a)

1.3.2. features of electrical equipment:

1.3.2.1. The design and construction of each motor shall be consistent with the operation conditions and maintenance requirements of the equipment it drives.

1.3.2.2. The rated power of the motor shall not be less than the capacity required for long-term continuous operation of the equipment driven by the motor, and the maximum torque guarantee value shall be 1.8 times of the rated torque.

1.3.3 features of instrument and control equipment:

1.3.3.1. Instruments and control equipment are qualified products identified by the state.

1.3.3.2. The instrument adopts legal unit of measurement. The analog output signal of all control devices is 4 ~ 20mA DC, and the switch output is passive contact signal, with capacity not less than 220V AC, 3A; 24 V DC, 1A.

1.3.3.3. Sequence control of start and stop process of coal feeder system, and reserve conditions and interfaces to participate in sequence control of coal pulverizing system.

1.3.3.4. The accuracy of measurement and control equipment system is ± 0.5% and ±1% respectively.

1.3.3.5. It is equipped with weighing speed sensor, coal flow detector of inlet coal falling pipe, belt coal breaking signal, etc., so that the working state of coal feeder can be comprehensively monitored.

1.3.3.6. The electric control box can be used for local manual, remote manual and remote automatic single or sequential control of coal feeder, and can switch between each other. At the same time, it has the functions of display, alarm and chain protection, and can output or receive signals to the remote. In addition, it also has 13 kinds of fault self diagnosis functions.

1.3.3.7. The coal gate is equipped with an electric control box installed locally, which can be controlled by local manual, remote manual and remote automatic control, and can switch to each other. At the same time, it has the functions of display, alarm and interlock protection, and can output or receive signals to the remote.

1.4. Structural features

The structure is a conveyor belt type coal feeder with electronic weighing and automatic speed regulation device, as shown in Fig. 16-1.

The electronic weighing coal feeder is composed of frame, feeding belt mechanism, chain cleaning scraper mechanism, weighing mechanism, coal blocking and coal breaking signal device, lubrication and electrical pipeline, microcomputer control cabinet, etc.

1.4.1. The engine base is composed of body, feeding port and discharging end door, side door and lighting lamp. The machine body is a sealed welded shell, which can withstand 0.34MPa explosion pressure and meet the requirements of NFPA code (B5F). A guide plate and baffle plate are set at the feed inlet of the machine body to form a certain section of coal flow on the belt after the coal enters the body. All parts that can contact with the coal are made of 0Cr18Ni9 stainless steel.

The gate body at the discharge end of the feed inlet is tightly pressed on the body with screws to keep the seal. The door can be opened to the left or right. All doors are equipped with observation windows and sprinklers are installed in the windows. When there is coal ash accumulated inside the window hole, it can be removed with compressed air or water through the nozzle. The lamp with sealed structure is used for lighting when observing the internal operation of the machine.

1.4.2. The feeding belt mechanism is composed of motor, reducer, belt drive drum, tension drum, belt support plate, belt tension device and feeding belt. The feeding belt has edges and ribs in the middle of the inner side. There are corresponding grooves in each drum to guide the belt well. At the end of the driving drum, a belt cleaning scraper is installed to scrape the coal adhered to the surface of the belt. The tension roller installed in the middle of the belt can keep a certain tension of the belt and get the best weighing effect; the tension of the belt changes with the change of temperature and humidity, which should be observed frequently, and the tension of the belt can be adjusted by using the tension rod. There is an indicator board in the side door of the engine base, and the center of the tension roller should be adjusted to the center of the indicator board.

The drive motor of feeding belt mechanism adopts special frequency conversion speed regulating motor (including speed measuring generator). Through frequency conversion controller, it forms an AC stepless speed regulation device with automatic adjustment function, which can carry out smooth stepless speed regulation in this wide range.

The feeding belt reducer is a cylindrical gear and worm gear two-stage reducer. The worm gear is lubricated by oil bath, and the gear is dripped through the worm shaft hole through the cycloid oil pump in the reducer box; the worm gear shaft end drives the belt drive drum through the pin coupling.

1.4.3. The coal breaking signal device is installed above the belt. When there is no coal on the belt, the cam on the signal device shaft will touch the limit switch due to the swing of the baffle on the signal device, so as to control the belt drive motor, or start the coal bunker vibrator, or return to the control room to indicate that there is no coal on the belt, which is determined by the user according to the requirements of the operation system; the coal cut-off signal can also be provided to stop The coal quantity accumulates, as well as prevents in the belt has the coal situation the fixed degree coal feeder.

The coal blocking signal device is installed at the outlet of the coal feeder, and its structure is the same as that of the coal cut-off signal device. When the coal flow is blocked to the outlet, the limit switch will send out a signal and stop the coal feeder.

1.4.4. The weighing mechanism is located between the feeding port of the coal feeder and the driving drum. The surfaces of the three weighing rollers are carefully processed, one of which is fixed on the body to form the weighing span; the other one is located in the middle of the weighing span and suspended on a pair of load sensors, and the coal weight on the belt is sent by the load sensor. The output signal of the calibrated load sensor represents the coal quality per unit length, while the frequency signal from the tachogenerator represents the speed of the belt. The coal feeding rate can be obtained by combining the two signals by the microcomputer control system.

The calibration block is built into the machine body (installed under the load sensor and the weighing idler). When the coal feeder is working, the calibration block is supported on the weighing arm and eccentric plate, and is separated from the weighing roller; when the calibration is required, rotate the handle of the weight calibration rod to make the eccentric plate rotate, and the weighing calibration block is suspended on the load sensor, so as to check whether the quality signal is accurate.

1.4.5. Chain cleaning scraper is used to clean the coal accumulated at the bottom of the coal feeder body. When the coal feeder is working, if there is coal ash binding inside the belt. After the self-cleaning tension roller, it falls down from the end face of the drum. Due to the seal air in the body of the coal feeder, under the action of the sealing air, the coal ash will accumulate at the bottom of the body. If it is not removed in time, it may cause spontaneous combustion.

The scraper chain is driven by the motor through the reducer, and the chain with wings scrapes the coal ash to the outlet of the coal feeder for discharge. The chain cleaning scraper runs continuously with the operation of the feeding belt. With this operation mode, the coal accumulation in the body can be minimized. At the same time, continuous cleaning can reduce coal feeding rate error, and continuous operation can also prevent chain pin from sticking and rusting.

The drive motor of scraper cleaning machine adopts precise electronic current relay for overload protection. When the scraper mechanism is overloaded, the current relay will cut off the power supply of the motor and stop the motor from rotating.

1.4.6. The inlet of the sealing air is located below the inlet of the coal feeder body, and the flange type interface is used for the user to connect with the sealing air. In the positive pressure operation system, the seal of the coal feeder itself is reliable, and it can be considered that there is no leakage. The coal feeder needs to seal the air to prevent the hot air from entering the coal feeder through the discharge port. The seal air pressure is the inlet pressure of the pulverizer plus 60 ~ 245Pa, and the required sealing air volume is the air leakage from the coal half through the feeding and dropping coal pipe and the air required by the pressure difference between the coal feeder and the coal pulverizer inlet. An internal thread interface is installed near the inlet of the coal feeder body. The pressure gauge can be connected here to measure the pressure value in the machine. When the pressure gauge is not connected, the screw plug is used for sealing.

If the seal air pressure is too low, hot air will enter into the coal feeder from the coal mill. In this way, coal ash will easily accumulate in the door frame or other protruding parts, which will cause spontaneous combustion. If the sealing air pressure is too high and the air volume is too large, the coal particles will be blown off from the belt, which will reduce the weighing accuracy and increase the load of cleaning the auxiliary plate. In addition, if the sealing air volume is too large, it is easy to generate dust mist in the observation hole, which is not conducive to observation. Therefore, the pressure of sealing air should be adjusted properly.

1.4.7. Except that the reducer is lubricated by oil immersion, the rest of the machine is lubricated with grease. The internal lubrication of the machine is connected to the outside of the machine by hose, so it can be lubricated without opening the machine door.

1.4.8. Hose device is used for electrical connecting pipe, and the cable enters into the body through the control box in the hose, and the sealing of the body is maintained.

1.4.9. The microcomputer control cabinet of coal feeder is installed on the machine body, and the power switch is installed in the cabinet to cut off the power supply of the machine.

1.4.10. In addition to the microcomputer control board, power supply board, signal conversion board and frequency conversion controller necessary for microcomputer control system, magnetic starter for thermal overload protection, transformer, fuse and relay are also installed in the microcomputer control cabinet. The surface of microcomputer control cabinet door is equipped with microcomputer display keyboard, switch SSC and FLS

 

2. Main technical parameters

The electronic weighing coal feeder is divided into three models, and the basic parameters are shown in table 16-1.

Table 16-1 basic parameters of electronic weighing coal feeder

Item details Parameters
Model of coal feeder 9218 9224 9236
Rated coal supply (t/h) 2~30 10~100 25~250
Nominal diameter of feed inlet (mm) 556 610 914
Nominal center moment of inlet and outlet (mm) 1829 2135 2743
Power of conveyor belt motor (kW) 2.2~3 3~4 4~7.5
Cleaning scraper motor power (kW) 0.37 0.37~0.55 0.55
Equipment weight (t) appa. 2.8 appa. 3.7 appa. 5

 

3. Equipment appearance and structural dimensions

The standard electronic weighing coal feeder and auxiliary equipment are shown in figure 16-2, general drawing in Figure 16-3 and maintenance space in figure 16-4

 

4. Selection method

The user mainly determines the model of the electronic weighing coal feeder through the required coal feeding amount. The detailed technical parameters of the standard 9224 electronic weighing coal feeder are as follows:

4.1. Output: provided by users.

4.2. Measurement accuracy: ±0.5%.

4.3. Control accuracy: ±1%

4.4. Shell pressure: 0.35Mpa

4.5. Coal feeding distance: 2135 mm

4.6. Inlet size: 609 (inner diameter) for coal feeder body and 928 (inner diameter) for coal bunker outlet coal valve.

4.7. Outlet dimensions: According to the size of coal mill outlet.

4.8. Overall dimension: 3360mx 100mx 1710mm.

4.9. Sealing air parameters: the normal air pressure is 500Pa higher than the outlet pressure of the coal mill; the normal air volume is 10m3 / min

4.10. Sealing air temperature: ambient temperature.

4.11. Motor (chain cleaning scraper) power: 0.37kW; voltage: 380V AC.

4.12. Feeding belt motor power: 4kW; voltage: 380V AC.

 

5. Scope of supply and ordering instructions

The scope of supply of the complete set of electronic weighing coal feeder includes all equipment, coal gate, pipeline and accessories between the coal outlet of coal hopper and the coal inlet of coal mill, including electric coal gate at coal hopper outlet (including electric device and control box), inlet coal falling pipe and pipe coupler, pipe accessories, electronic weighing coal feeder (including motor, reducer, weighing device, coal breaking signal device and blocking) Coal signal device, metering device, cleaning device, etc.), coal dropping pipeline and pipe coupling between coal feeder outlet and coal inlet of coal mill, pipe accessories, electric outlet coal gate (including electric device and control box), necessary electrical components in the system, flange (including counter flange) and accessories of interface with coal hopper and coal mill. If the user has other requirements, they can also be negotiated in the contract.